Control handle with rotational cam mechanism for contraction/deflection of medical device

ABSTRACT

A medical device has a distal member with a configuration that can be changed by means of a control handle with a control assembly employing a rotational cam, a shaft, and a pulley, where the rotational cam is rotationally mounted on a portion of the control handle for rotation by a user. The rotational cam operates on the shaft to move it proximally or distally depending on the direction of rotation which in turn rotates the pulley to draw or release a puller wire to change the configuration of the distal member of the medical device. The shaft is oriented along a diameter of the control handle. The shaft has two ends which extends through two axial guide slots in the portion of the control handle to sit two opposing helical tracks formed on inner surface of the rotational cam. The guide slots are parallel with the longitudinal axis of the control handle and therefore maintain the shaft&#39;s diametrical orientation as the rotational cam is rotated to move the shaft proximally or distally. Actuation of the puller wire by means of the control assembly can result in a change of the distal member&#39;s configuration, including deflection, contraction and/or expansion.

FIELD OF INVENTION

This invention relates to a catheter, in particular, a control handlehaving multiple control mechanisms for deflecting and contractingportions of a medical device.

BACKGROUND

Electrode catheters have been in common use in medical practice for manyyears. They are used to stimulate and map electrical activity in theheart and to ablate sites of aberrant electrical activity. Atrialfibrillation is a common sustained cardiac arrhythmia and a major causeof stroke. This condition is perpetuated by reentrant waveletspropagating in an abnormal atrial-tissue substrate. Various approacheshave been developed to interrupt wavelets, including surgical orcatheter-mediated atriotomy. Prior to treating the condition, one has tofirst determine the location of the wavelets. Various techniques havebeen proposed for making such a determination, including the use ofcatheters with a mapping assembly that is adapted to measure activitywithin a pulmonary vein, coronary sinus or other tubular structure aboutthe inner circumference of the structure. One such mapping assembly hasa tubular structure comprising a generally circular main regiongenerally transverse and distal to the catheter body and having an outercircumference and a generally straight distal region distal to the mainregion. The tubular structure comprises a non-conductive cover over atleast the main region of the mapping assembly. A support member havingshape-memory is disposed within at least the main region of the mappingassembly. A plurality of electrode pairs, each comprising two ringelectrodes, are carried by the generally circular main region of themapping assembly.

In use, the electrode catheter is inserted into a guiding sheath whichhas been positioned a major vein or artery, e.g., femoral artery, andguided into a chamber of the heart. Within the chamber, the catheter isextended past a distal end of the guiding sheath to expose the mappingassembly. The catheter is maneuvered through movements that includedeflection of a distal portion of the catheter so that the mappingassembly is positioned at the tubular region in the heart chamber. Theability to control the exact position and orientation of the catheterand also the configuration of the mapping assembly is critical andlargely determines how useful the catheter is.

Steerable catheters are generally well-known. For example, U.S. Pat. No.Re 34,502 describes a catheter having a control handle comprising ahousing having a piston chamber at its distal end. A piston is mountedin the piston chamber and is afforded lengthwise movement. The proximalend of the elongated catheter body is attached to the piston. A pullerwire is attached to the housing and extends through the piston, throughthe catheter body, and into a tip section at the distal end of thecatheter body. The distal end of the puller wire is anchored in the tipsection of the catheter. In this arrangement, lengthwise movement of thepiston relative to the housing results in deflection of the catheter tipsection.

The design described in U.S. Pat. No. RE 34,502 is generally limited toa catheter having a single puller wire. If bi-directional deflection isdesire, more than one puller wire becomes necessary. Moreover, if morecontrol is desired, such as contraction of the mapping assembly, anadditional puller wire is needed. Space is limited within a controlhandle and operation of puller wire control mechanisms must notinterfere with components that extend through the control handle, suchas lead wires, cables, and irrigation tubing. Moreover, it is desirablethat the control mechanisms be arranged such that the catheter can beoperated single-handedly by the user. Accordingly, a desire exists for acontrol handle capable of moving three puller wires for at least twoindependent movements, such as bi-directional deflection of the cathetershaft and contraction of the mapping assembly, preferably through asingle-handed manipulation of the user. A further desire exists for adeflection/contraction mechanism without excessive stress or kinking tothe tensile component by which deflection/contraction is accomplished,whether it is a puller wire, a contraction wire, or another component.

SUMMARY OF THE INVENTION

The present invention is directed to a medical device which has a distalmember with a configuration that can be changed by means of a controlhandle with a control assembly employing a rotational cam, a shaft, anda pulley, where the rotational cam is rotationally mounted on a portionof the control handle for rotation by a user. The rotational camoperates on the shaft to move it proximally or distally depending on thedirection of rotation which in turn rotates the pulley to draw orrelease a puller wire to change the configuration of the distal memberof the medical device. The shaft is oriented along a diameter of thecontrol handle. The shaft has two ends which extends through two axialguide slots in the portion of the control handle to sit two opposinghelical tracks formed on inner surface of the rotational cam. The guideslots are parallel with the longitudinal axis of the control handle andtherefore maintain the shaft's diametrical orientation as the rotationalcam is rotated to move the shaft proximally or distally. Actuation ofthe puller wire by means of the control assembly can result in a changeof the distal member's configuration, including deflection, contractionand/or expansion.

In one embodiment, a catheter for use in a patient's heart, especiallyfor mapping a tubular region of the heart, includes a catheter body anda deflectable intermediate section distal the catheter body. Distal theintermediate section is a mapping assembly that has a generally circularportion adapted to sit on or in a tubular region of the heart. A controlhandle of the catheter allows for single-handed manipulation of variouscontrol mechanisms that can deflect the intermediate section andcontract the mapping assembly by means of a deflection control assemblyand a rotational control assembly. The deflection control assembly has adeflection arm and a rocker member. The rotational control assembly hasan outer rotational cam, a shaft and a pulley. A pair of puller membersare responsive to the deflection control assembly to bi-directionallydeflect the intermediate section. A third puller member is responsive tothe rotational control assembly to contract the generally circularportion of the mapping assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings. It isunderstood that selected structures and features have not been shown incertain drawings so as to provide better viewing of the remainingstructures and features.

FIG. 1 is a top plan view of one embodiment of the catheter of thepresent invention.

FIG. 2 a is a side cross-sectional view of an embodiment of a junctionof a catheter body and an intermediate section, taken along a firstdiameter.

FIG. 2 b is a side cross-sectional view of the embodiment of thejunction of FIG. 2 a, taken along a second diameter generallyperpendicular to the first diameter.

FIG. 3 is a side view of a distal portion of the catheter of FIG. 1,including an intermediate section and a mapping assembly.

FIG. 4 is a longitudinal cross-sectional view of the intermediatesection of FIG. 3, taken along line 4-4.

FIG. 5 is a schematic view of the mapping assembly showing onearrangement of the ring electrodes.

FIG. 6 is a longitudinal cross-sectional view of the mapping assembly ofFIG. 3 along line 6-6.

FIG. 7 is a side cross-sectional view of an embodiment of a distal endof the mapping assembly of FIG. 3.

FIG. 8 a is a side cross-sectional view of an embodiment of a junctionbetween the intermediate section and the mapping assembly, taken along afirst diameter.

FIG. 8 b is a side cross-sectional view of an embodiment of a junctionbetween the intermediate section and the mapping assembly, taken along asecond diameter generally perpendicular to the first diameter.

FIG. 9 is a top plan view of an embodiment of a control handle housinghalf including an embodiment of a deflection control assembly.

FIG. 10 is a top perspective view of an embodiment of a rocker member ofa deflection control assembly.

FIG. 11 is a bottom perspective view of an embodiment of a rockermember.

FIG. 12 is a side view of an embodiment of a pulley of a deflectioncontrol assembly.

FIG. 13 a-13 c are schematics of an embodiment of the deflection controlassembly in neutral and rotated configurations.

FIG. 14 is a longitudinal cross section of an embodiment of thedeflection control assembly and tension control assembly mounted on acontrol handle.

FIG. 14 a is a detailed view of a portion of FIG. 14, including anembodiment of a retaining nut and a tension screw.

FIG. 15 is a partial perspective view of an embodiment of a firstcontrol handle housing half.

FIG. 16 is a perspective view of an embodiment of a deflection arm.

FIG. 17 is a perspective view of an embodiment of a tension controldial.

FIG. 18 is a perspective view of an embodiment of a locking plate.

FIG. 19 is a partial perspective view of a portion of an embodiment of acontrol handle.

FIG. 20 is a partial perspective view of a portion of an embodiment of adeflection arm and a tension control member mounted on a control handle.

FIG. 21 is a partial perspective view of a portion of an embodiment of asecond control handle housing half and a retaining nut, the secondcontrol housing half adapted to oppose the first control handle housinghalf.

FIG. 22 is a perspective view of the tension control dial of FIG. 17 andlocking plate of FIG. 18 as assembled.

FIG. 23 is a perspective view of an embodiment of a rotational controlassembly.

FIG. 24 is an exploded perspective view of the rotational controlassembly of FIG. 23.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the present invention is directed to a catheter 10with multiple control capabilities for mapping and/or ablation of theheart. In the illustrated embodiment of FIG. 1, a catheter 10 comprisesan elongated catheter body 12, a deflectable intermediate section 14 ata distal end of the catheter body 12, a tip section 15 including amapping assembly 17 at a distal end of the intermediate section 14, anda multi-functional control handle 16 at a proximal end of the catheterbody 12 for controlling portions of the catheter, for example,deflecting the intermediate section 14 and contracting the mappingassembly 17.

With reference to FIGS. 2A and 2B, the catheter body 12 comprises asingle, central or axial lumen 18. The catheter body 12 is flexible,i.e., bendable, but substantially non-compressible along its length. Thecatheter body 12 may be of any suitable construction and made of anysuitable material. A suitable construction comprises an outer wall 22made of a polyurethane or nylon. The outer wall 22 comprises an imbeddedbraided mesh of stainless steel or the like to increase torsionalstiffness of the catheter body 12 so that, when the control handle 16 isrotated, the tip section of the catheter 10 will rotate in acorresponding manner.

The outer diameter of the catheter body 12 is not critical, but ispreferably no more than about 8 French. Likewise the thickness of theouter wall 22 is not critical. The inner surface of the outer wall 22 islined with a stiffening tube 20, which can be made of any suitablematerial, e.g., polyimide. The stiffening tube 20 is held in placerelative to the outer wall 22 at the proximal end of the catheter body12. A first glue joint 23 is made between the distal ends of thestiffening tube 20 and the outer wall 22 by a fast drying glue, e.g.Super Glue®. Thereafter a second glue joint 25 is formed between theproximal ends of the stiffening tube 20 and outer wall 22 using a slowerdrying but stronger glue, e.g., polyurethane.

The stiffening tube, along with the braided outer wall 22, providesimproved torsional stability while at the same time minimizing the wallthickness of the catheter, thus maximizing the diameter of the singlelumen. The outer diameter of the stiffening tube 20 is about the same asor slightly smaller than the inner diameter of the outer wall 22.Polyimide tubing is suitable because it may be very thin walled whilestill providing very good stiffness. This maximizes the diameter of thecentral lumen 18 without sacrificing strength and stiffness. Polyimidematerial is typically not used for stiffening tubes because of itstendency to kink when bent. However, it has been found that, incombination with an outer wall 22 of polyurethane, nylon or othersimilar material, particularly having a stainless steel braided mesh,the tendency for the polyimide stiffening tube 20 to kink when bent isessentially eliminated with respect to the applications for which thecatheter is used.

In one embodiment, the outer wall 22 has an outer diameter of about0.092 inch and an inner diameter of about 0.063 inch and the polyimidestiffening tube 20 has an outer diameter of about 0.0615 inch and aninner diameter of about 0.052 inch.

As shown in FIGS. 2A, 2B and 4, the intermediate section 14 comprises ashorter section of tubing 19 with multiple off-axis lumens, for example,first, second, third and fourth lumens 30, 31, 32 and 33. The tubing 19is made of a suitable non-toxic material which is preferably moreflexible than the catheter body 12. A suitable material for the tubing19 is braided polyurethane, i.e., polyurethane with an embedded mesh ofbraided stainless steel or the like. The outer diameter of theintermediate section 14, like that of the catheter body 12, ispreferably no greater than about 8 French. The size of the lumens is notcritical. In one embodiment, the intermediate section has an outerdiameter of about 7 French (0.092 inch) and the lumens are generallyabout the same size, having a diameter of about 0.022 inch, or selectedlumens can have a slightly larger diameter of about 0.036 inch.

A means for attaching the catheter body 12 to the intermediate section14 is illustrated in FIGS. 2A and 2B. The proximal end of theintermediate section 14 comprises an inner counter bore 24 that receivesthe outer surface of the polyimide stiffener 20. The intermediatesection 14 and catheter body 12 are attached by glue 29 or the like.

As shown in FIGS. 2A and 2B, extending through the single lumen 18 ofthe catheter body 12 are various components, for example, lead wires andmultiple puller members, and any other wires or cables. Longitudinalmovement of the puller members relative to the catheter body 12 enableuser control of various parts of the catheter via the control handle. Inone embodiment, the puller members include a pair of deflection pullermembers 42 for deflecting the intermediate section 14 and a contractionpuller member 35 for adjusting the mapping assembly 17 of the tipsection 15.

A single lumen catheter body 12 can be preferred over a multi-lumen bodybecause the single lumen 18 body can permit better tip control whenrotating the catheter 10. The single lumen 18 permits the componentspassing therethrough to float freely within the catheter body. If suchcomponents were restricted within multiple lumens, they can build upenergy when the handle 16 is rotated, resulting in the catheter body 12having a tendency to rotate back if, for example, the handle isreleased, or if bent around a curve, to flip over, either for which areundesirable performance characteristics.

A deflection puller member 42 extends through the central lumen 18 ofthe catheter body 12 and into the second lumen 31 of the intermediatesection 14. Another deflection puller member 42 extends through thecentral lumen 18 and into the fourth lumen 33 of the intermediatesection 14. The distal ends of the deflection puller members 42 areanchored to the wall of the tubing 19 near the distal end of theintermediate section 14 by means of T-anchors 83 (FIG. 8B). In theintermediate section 14, each deflection puller members 42 extendsthrough a plastic, e.g., Teflon®™, sheath 81, which prevents thedeflection puller members 42 from cutting into the wall of the tubing 19of the intermediate section 14 when the intermediate section 14 isdeflected.

As shown in FIG. 2B, compression coils 44 in surrounding relation to thedeflection puller members 42 extend from the proximal end of thecatheter body 12 to the proximal end of the intermediate section 14. Thecompression coils 44 are made of any suitable metal, e.g., stainlesssteel. The compression coils 44 are tightly wound on itself to provideflexibility, i.e., bending, but to resist compression. The innerdiameter of the compression coils 44 is preferably slightly larger thanthe diameter of the puller wires 42. For example, when a puller member42 has a diameter of about 0.007 inches, the compression coil 44preferably has an inner diameter of about 0.008 inches. The Teflon®™coating on the puller member 42 allows them to slide freely within thecompression coils 44. The outer surface of the compression coils 44 iscovered by a flexible, non-conductive sheath 27 to prevent contactbetween the compression coils 44 and other components, such as leadwires and cables, etc. A non-conductive sheath can be made of polyimidetubing.

The compression coils 44 are anchored at their proximal ends to theproximal end of the stiffening tube 20 in the catheter body 12 by gluejoint 50 (FIG. 2B) and at its distal end near the proximal end of theintermediate section 14 in the second lumen 31 and fourth lumen 33 byglue joints 49 (FIG. 2B).

With reference to FIG. 3, at the distal end of the intermediate shaft 14is the mapping assembly 17. The mapping assembly 17 comprises agenerally straight proximal region 38 and a generally circular mainregion 39. The proximal region 38 is mounted on the intermediate section14, as described in more detail below, so that it is generally a linearextension of the intermediate section 14. In one embodiment, theproximal region 38 has an exposed length, e.g., not contained within theintermediate section 14, ranging from about 3 mm to about 12 mm, morepreferably about 3 mm to about 8 mm, still more preferably about 5 mm,but can vary as desired.

The generally circular main region 39 is generally traverse, if not alsoperpendicular, to the catheter body 12. The generally circular mainregion 39 can form a flat circle or can be very slightly helical. In oneembodiment, the main region 39 has an outer diameter ranging from about10 mm to about 25 mm, more preferably about 12 mm to about 20 mm. Thegenerally circular main region 39 can curve in a clockwise direction ora counterclockwise direction. As shown in FIGS. 5, 6 and 7, the mappingassembly 17 is formed of a non-conductive cover or tubing 52 which canhave any cross-sectional shape as desired. The non-conductive cover 52can be made of any suitable material, and is preferably made of abiocompatible plastic such as polyurethane or PEBAX. The non-conductivecover 52 can be pre-formed into the desired generally circular shape ofthe generally circular main region 39. Alternatively, the shape of thegenerally circular main region 39 can be defined by a wire or othercomponent extending through the non-conductive cover 52.

In the depicted embodiment, a pre-formed support member 54 extendsthrough the non-conductive cover 52 to define the shape of the generallycircular main region 39. The support member 54 is made of a materialhaving shape-memory, i.e., that can be straightened or bent out of itsoriginal shape upon exertion of a force and is capable of substantiallyreturning to its original shape upon removal of the force. On suitablematerial for the support member 54 is a nickel/titanium alloy. Suchalloys typically comprise about 55% nickel and 45% titanium, but maycomprise from about 54% to about 57% nickel with the balance beingtitanium. A suitable nickel/titanium alloy is Nitinol, which hasexcellent shape memory, together with ductility, strength, corrosionresistance, electrical resistivity and temperature stability.

A series of ring electrodes 26 are mounted on the non-conductive cover52 of the generally circular main region 39 of the mapping assembly 17,as shown in FIG. 5. The ring electrodes 26 can be made of any suitablesolid conductive material, such as platinum or gold, or a combination ofplatinum and iridium, and mounted onto the non-conductive cover 52 withglue or the like. Alternatively, the ring electrodes 26 can be formed bycoating the non-conductive cover 52 with an electrically conductingmaterial, like platinum, gold and/or iridium. The coating can be appliedusing sputtering, ion beam deposition or an equivalent technique. Asuitable mapping assembly is described in U.S. Pat. No. 7,274,957, theentire disclosure of which is hereby incorporated by reference. Ifdesired, additional electrodes (not shown) could be mounted along theintermediate section 14 and/or the generally straight proximal section38.

The contraction puller member 35, for example, a contraction pullerwire, is provided to contract the generally circular main region 39 tothereby change or reduce its diameter, for example, when mapping orablating circular or tubular regions of the heart. The contraction wire35 has a proximal end anchored in the control handle 16, which is usedto manipulate the contraction wire as described further below. Thecontraction wire 35 extends through the central lumen 18 of the catheterbody 12, through the third lumen 32 of the intermediate section 14 andinto the non-conductive cover 52 of the mapping assembly 17. The portionof the contraction wire 35 extending through the non-conductive cover 52is positioned on the side of the generally circular main region 39closer to the center of the generally circular main region, as bestshown in FIG. 6. The center of the generally circular main region refersto the center of the circle formed by the generally circular mainregion. With this arrangement, contraction of the generally circularmain region 39 is dramatically improved over arrangements where theposition of the contraction wire 35 is not so controlled.

As shown in FIGS. 5 and 6, within the mapping assembly 17, thecontraction wire 35 extends through a plastic tube 55. In oneembodiment, the plastic tube 55 comprise three layers, including aninner layer of polyimide over which a braided layer is formed, thebraided layer comprising a braided stainless steel mesh or the like, asis generally known in the art. The braided layer enhances the strengthof the plastic tube 55, reducing the tendency for contraction wire 35 tostraighten the preformed curve of the mapping assembly 17. A thinplastic layer of polytetrafluoroethylene is provided over the braidedlayer to protect the braided layer from getting tangled with the leadwires 40 within the non-conductive cover 52. The plastic tube 55 has aproximal end anchored to the distal end of the intermediate section 14in the third lumen 32 by glue or the like (FIG. 8 a). The support member54 extends through the plastic tube 55 with the contraction wire 35(FIG. 8 a). The distal ends of the support member 54 and the contractionwire 35 are soldered or otherwise attached to a small stainless steeltube 53 (FIG. 7). With this arrangement, the relative positions of thecontraction wire 35 and the support member 54 can be controlled so thatthe contraction wire can be positioned on the side of the generallycircular region 39 closer to the center of the generally circular region39, as described above. The contraction wire 35 on the inside of thecurve pulls the support member 54 to the inside of the curve, enhancingcontraction of the generally circular region 39. Further, when theplastic tube 55 includes a braided layer, it keeps the contraction wire35 from tearing through the non-conductive cover 52.

A third compression coil 46 is situated within the catheter body 12 andintermediate section shaft 14 in surrounding relation to the contractionwire 35 (FIG. 2A). The third compression coil 46 extends from theproximal end of the catheter body 12 to near the distal end of the thirdlumen 32 of the intermediate section 14. The third compression coil 46is made of any suitable metal, e.g., stainless steel, and is tightlywound on itself to provide flexibility, i.e., bending, but to resistcompression. The inner diameter of the third compression coil 46 ispreferably slightly larger than the diameter of the contraction wire 35.The outer surface of the compression coil 46 is covered by a flexible,non-conductive sheath 68, e.g., made of polyimide tubing. The thirdcompression coil 46 can be formed of a wire having a square orrectangular cross-sectional area, which makes it less compressible thana compression coil formed from a wire having a circular cross-sectionalarea. As a result, the third compression coil 46 keeps the catheter body12, and particularly the intermediate section 14, from deflecting whenthe contraction wire 35 is manipulated to contract the mapping assembly17 as it absorbs more of the compression.

The third compression coil 46 is anchored at its proximal end to theouter wall 20 of the catheter body 12 by the proximal glue joint 50 andto the intermediate section 14 by distal glue joint 72.

It is understood that glue joints throughout the catheter 10 maycomprise polyurethane glue or the like. The glue may be applied by meansof a syringe or the like through a hole made in the tubing walls. Such ahole may be formed, for example, by a needle or the like that puncturesthe tubing walls where the needle is heated sufficiently to form apermanent hole. The glue is then introduced through the hole to wickaround the component(s) within the tubing to form a glue joint about theentire circumference of the component(s).

In the depicted embodiment of FIG. 7, the distal end of the mappingassembly 17 is sealed closed with a dome 51 of polyurethane glue or thelike. A short ring 56, made of metal or plastic, and e.g., polyamide, ismounted within the distal end of the non-conductive cover 52. The shortring 56 prevents the distal end of the non-conductive cover 52 fromcollapsing, there by maintaining the diameter of the non-conductivecover at its distal end.

At the junction of the intermediate section 14 and the mapping assembly17 as shown in FIGS. 8 a and 8 b, the non-conductive cover 52 isattached to the intermediate section 14 by glue or the like. The plastictube 55 has its proximal end inserted and glued in the distal end of theintermediate section 14. The glue (not shown) from the plastic tube 55can further serve to anchor the distal end of the third compression coil46 in place within the third lumen 32. The support member 54 extendsfrom the third lumen 32 into the plastic tube 55 within thenon-conductive cover 52. The proximal end of the support member 54terminates a short distance proximally from the distal end of the thirdlumen 32, approximately about 5 mm, so as not to adversely affect theability of the intermediate section 14 to deflect. However, if desired,the proximal end of the support member 54 can extend proximally furtherinto the intermediate section 14 and/or the catheter body 12.

The lead wires 40 attached to the ring electrodes 26 extend through thefirst lumen 30 of the intermediate section 14 (FIG. 2A), through thecentral lumen 18 of the catheter body 12, through the control handle 16,and terminate at their proximal end in a connector (not shown) which isconnected to an appropriate monitor or other device for receiving anddisplaying the information received from the ring electrodes 26. Theportion of the lead wires 40 extending through the central lumen 18 ofthe catheter body 12, control handle 16 and proximal end of theintermediate section 14 is enclosed within a protective sheath 62, whichcan be made of any suitable material, such as polyimide. The protectivesheath 62 is anchored at its distal end to the proximal end of theintermediate section 14 by gluing it in the lead wire lumen 30 withpolyurethane glue or the like to form glue joint 73.

The lead wires 40 are attached to the ring electrode 26 by anyconventional technique. In one embodiment, each ring electrode 26 ismounted by first forming a hole in the non-conductive cover 52. Anelectrode lead wire 40 is fed through the hole, and the ring electrode26 is welded in place over the lead wire and non-conductive cover 52.

With reference to FIG. 1, the control handle 16 comprises a generallyelongated handle housing, which can be made of any suitable rigidmaterial, such as plastic configured through a suitable molding process.In the illustrated embodiment, the housing includes two opposing halves16 a and 16 b that generally mirror each other and are joined by glue,sonic welding or other suitable means along a longitudinal peripheralseam 28 around the housing. In the illustrated embodiment, the crosssection of the handle 16 formed by the opposing halves changes along thelength of the handle. A more distal portion 112 has a smaller, generallyrectangular cross section. A mid-portion 114 has a larger, generallyrectangular cross section. A more proximal portion 116 has a generallycircular cross section.

In the illustrated embodiment of FIGS. 1 and 9, the control handle 16houses components of a deflection control assembly 74 in the mid-portion114. The deflection control assembly includes a deflection member or arm75 that can be directly manipulated by an operator to control deflectionof the intermediate section 14. The deflection arm 75 is rotatable aboutan axis 76 that is generally transverse or perpendicular to thelongitudinal axis of the control handle. The deflection control assembly74 has a rotatable rocker member 78 that acts on the deflection pullermembers 42 to deflect the intermediate section 14.

The rocker member 78 has a length L dimension, a width W dimension and athickness T dimension (FIGS. 10 and 11). Along its thickness dimensionT, the rocker member 78 is configured with two opposing annularformations 140 a and 140 b that define a central hole or passage 143that extends through its entire thickness. The central hole 143 isaligned with the rotational axis 76 of the deflection arm 75. Along itslength dimension L, the rocker member 78 also has two smaller holes 146that oppose each other across the central hole 143. In each hole sits apulley 147, for example, a snap bearing (FIG. 12), that has a rotationalaxis parallel to the axis 76. Each deflection puller member 42 entersthe rocker member through slots 148 and a portion is wound around arespective pulley 147.

As understood by one of ordinary skill in the art, the rocker member 78and the pulleys 147 are arranged such that rotation of the rocker memberin one direction about the axis 76 draws back one puller member 42 todeflect the intermediate section 14 in that direction. With reference toFIGS. 13 a-13 c, as the rocker member 78 is rotated by means of thedeflection arm (as represented by line 75), the pulleys 147 aredisplaced from a neutral position (FIG. 13 a) with one pulley 147drawing a puller member 42 on one side of the catheter body 12 againstits anchored proximal end for deflecting the intermediate section 14toward that side (FIGS. 13 b and 13 c).

Each deflection puller member 42 may comprise multiple segments. Asillustrated in FIG. 9, each deflection puller member has a distal pullerwire 42 a and a proximal fiber 42 b that are joined or connected at alocation within the control handle 16 distal the rocker member 78. Thepuller wire 42 a and the tensile fiber 42 b of each deflection pullermember are connected or secured to each other by a connector 154, e.g.,a crimped brass ferrule covered by shrink tubing. Each puller wire 42 aextends through the catheter body 12 and the intermediate section 14.Each tensile fiber 42 b extends inside the control handle 16. In thismanner, it is the more flexible tensile fibers 42 b that interact withthe pulleys 147 and undergo repeated bending and straightening duringdeflection operations, as they are less prone to bending stress andfatigue failure.

Each puller wire 42 a is made of any suitable metal, such as stainlesssteel or Nitinol. Preferably each puller wire has a low frictioncoating, such as a coating of Teflon®™ or the like. Each puller wire hasa diameter preferably ranging from about 0.006 inch to about 0.012 inch.Preferably both of the puller wires have the same diameter. Flat pullerwires may be used in place of round puller wires. Their cross sectionaldimensions should be such that they provide comparable tensile strengthsas round puller wires.

Each tensile fiber 42 b may be of a high modulus fiber material,preferably having an ultimate tensile strength substantially in therange of 412-463 ksi (2480-3200 Mpa) such as High Molecular DensityPolyethylene (e.g., Spectra™ or Dyneema™), a spun para-aramid fiberpolymer (e.g., Kevlar™) or a melt spun liquid crystal polymer fiber rope(e.g., Vectran™), or a high strength ceramic fiber (e.g., Nextel™). Theterm fiber is used herein interchangeably with the term fibers in thatthe tensile fiber may be of a woven or braided construction. In anycase, these materials tend to be flexible, providing suitable durabilitywhen used in wrapped engagement with the pulleys and the like forgreater throw in deflecting the catheter tip. Further, they aresubstantially non-stretching, which increases the responsiveness to themanipulation of the control handle, and nonmagnetic so that theygenerally appear transparent to an MRI. The low density of the materialcauses it to be generally transparent to an x-ray machine. The materialscan also be nonconductive to avoid shorting. Vectran™, for example, hashigh strength, high abrasion resistance, is an electrical insulator,nonmagnetic, is polymeric, and has low elongation under sustainedloading conditions.

In the illustrated embodiment of FIG. 9, each tensile fiber 42 b extendsproximally from the connector 154 toward the rocker member 78 where eachis wound around a respective pulley 147 and turns about 180 degrees todouble back toward the distal end of the control handle. Each proximalend of the tensile fiber 42 b is anchored by an anchor assembly 90 thatincludes a pair of racks 92, a slug 94 and a stop 96. The proximal endof each tensile fiber 42 b extends between a channel 91 defined by thepair of racks 92, and the proximal end of each tensile fiber is encasedwithin a molded member or slug 94 sized to fit in and translate in thechannel 91. Proximal the slug are the stops 96 that are adjustablypositioned in a selected location along the racks 92, for example, bymeans of interlocking teeth 98 formed in the racks and the stops toreleasably lock in the selected position against movement. The stops 96are formed so that each respective tensile fiber 42 b can slide throughor below them while blocking the slugs 94 from moving proximally pastthem. Accordingly, the stops 96 limit the proximal movement of the slugs94 and anchor the proximal ends of the tensile fibers 42 b to effectuatedeflection when each is drawn proximally by the deflection controlassembly 74. During assembly of the control handle 16, before the twohousing halves 16 a, 16 b are joined, the stops 96 are selectivelypositioned between the racks 92 to achieve a desirable tension in eachtensile member. The interlocking teeth 98 of the racks 92 and stops 96allow for fine adjustments in setting the tension.

The construction and assembly of the deflection control assembly 74including the deflection aim 75 and a tension adjustment member 101 onthe control handle 16 are described as follows. With reference to FIGS.14 and 14 a, the rocker member 78 of the assembly 74 is situated betweenthe two halves 16 a and 16 b of the control handle 16, with each of itsannular formations 140 a and 140 b extending respectively through anopening 120 a, 120 b formed in the distal portion 114 of each housinghalf 16 a and 16 b.

The annular formation 140 a has recesses 160 (FIG. 10) exposed throughthe opening 120 a (FIG. 15) that receive protrusions 152 projecting froma facing surface 154 of the deflection arm 75 (FIG. 16) to rotationallycouple the deflection arm 75 and the rocker member 78. The protrusions152 can snap fit into the recesses 160 and/or be secured by adhesives,glue, sonic welding and the like. A central circular protrusion 156 fromthe deflection arm 75 fits into the hole 143 circumscribed by theannular formation 140 a of the rocker member 78. A suitable deflectionassembly and control handle are described in co-pending U.S. applicationSer. No. 12/346,834, filed Dec. 30, 2008, entitled DEFLECTABLE SHEATHINTRODUCER, the entire disclosure of which is hereby incorporated byreference. Another suitable deflection assembly with deflectionsensitivity is described in co-pending U.S. application Ser. No.12/211,728, filed Sep. 16, 2008, entitled CATHETER WITH ADJUSTABLEDEFLECTION SENSITIVITY, the entire disclosure of which is herebyincorporated by reference. Therein, a cam that is responsive to adeflection sensitivity knob can vary the separation distance between thetwo pulleys 147, thereby changing the deflection sensitivity of thedeflection arm.

Opposing the deflection arm 75 is the deflection tension adjustmentmember or dial 101 (FIGS. 17 and 20) which is coupled to and indirectlyengaged with the rocker member 78 by various mechanisms and parts andallows an operator to adjust the ease with which the deflection arm 75can be rotated. Mounted primarily on the housing half 16 b, theillustrated embodiment of a tension adjustment assembly 100 includes theadjustment dial 101 (FIG. 17), a locking plate 102 (FIG. 18), a tensioncap screw 103, a retaining nut 136 and a washer 119 (see FIGS. 14 and 14a). A user rotates the dial 101 to adjust the tightness or tension ofthe rotational movement of deflection arm 75 by effectively compressingor releasing the rocker member 78 against the washer 119 (e.g., aBelleville type) and the control handle housing half 16 b.

The dial 101 has a generally circular cross section with acircumferential edge 115 having a friction-inducing surface (FIG. 17). Acentral circular protrusion 105 and a plurality of prongs 106 (FIG. 17)situated along a diameter of the dial project from a surface 104 of thedial 101.

The locking plate 102 is sandwiched between the dial 101 and the handlehousing 16 b (FIG. 20). The locking plate 102 (FIG. 18) has a centrallarger hole 107 and two smaller holes 108, all three of which extendthrough the entire thickness of the locking plate. The two prongs 106 ofthe dial 101 are adapted to be inserted through the smaller holes 108 inthe plate 102 (FIG. 21) and received in semi-circular grooves 109 (FIG.19) formed in an outer surface of the housing half 16 b. The grooves 109limit the degree of rotation of the dial 101 in clockwise andcounterclockwise directions. The central hole 107 of the plate 102 (FIG.18) has different cross-sections that include a larger circularcross-section 107 a and a smaller circular cross-section 107 b. Thelarger circular cross-section 107 a receives a head 112 of a cap screw103, and the smaller circular cross-section 107 b receives a threadedbody 115 of the cap screw 103 (FIG. 14 a).

The threaded body 115 of the cap screw 103 extending through the centralhole 107 of the locking plate 102 engages the retaining nut 136 situatedin the opening 143 of the rocker member 78. A head 115 of the nut abutsand is anchored against a neck 132 formed in the inner surface of theopening 143 of the rocker member 78. The opening 120 b in the housinghalf 16 b (FIG. 21) has a larger cross section 122 and a smaller crosssection 124. The smaller cross section 124 has a polygonal shape whichmatches a polygonal (e.g., hexagonal) end 126 of the nut 136 so that thenut 136 is effectively locked against rotation relative to the housinghandle 16 b.

The central protrusion 105 of the dial 101 (FIG. 17) forms a press orinterference fit with the head 112 of the cap screw 103 to createrotational alignment between these two components. The prongs 106 of thedial 101 lock and rotationally couple the dial 101 and the lock plate102, and the cap screw 103 is rotationally coupled to the locking plate102. Coupling of the dial 101 and the locking plate 102 may also beachieved by means of welding the two components together. In that case,the prongs 106 need not protrude from the dial 101 but can insteadextend from the locking plate 102.

Between the polygonal end 126 of the nut 136 and the housing handle 16 bis the washer 119 whose compression against the nut 136 and the housinghandle 16 b is adjustable by the user's rotation of the dial 101 whichtightens or releases the engagement between cap screw 103 and the nut136, thus increasing or decreasing the ease with which the rocker member78 and hence the deflection arm 75 can be rotated.

Components that extend through the control handle, including, forexample, the lead wires 40 and the contraction wire 35 also enter thecontrol handle at the distal end. In the illustrated embodiment of FIG.9, these components extend along the longitudinal axis of the controlhandle. A protective tubing 152 through which the components extend canbe provided, positioned between the two deflection puller members 42 andthrough a channel 150 form through the width dimension W of the rockermember 78 (FIG. 11). Distal and proximal portions of the channel 150have indents, e.g., triangular or wedge-shaped, 151 (FIGS. 9 and 11) toallow the rocker member 78 to rotate freely within a predetermined rangeof angles, e.g., about ±45 degrees of the longitudinal axis of thecontrol handle 16, without interference by the tubing 152 and thecomponents therethrough.

Alternatively, the components extending through the control handle, withthe exception of the contraction wire 35, are routed on an off-axis path153 diverging from the deflection puller members 42 at entry into thedistal end of the control handle 16. The components thus extend alongthe periphery of the housing handle, bypassing the rocker member 78.

It is understood that the distance between the distal end of thecompression coils 44 and the distal anchor sites of each deflectionpuller members 42 in the intermediate section 14 determines thecurvature of the intermediate section 14 in the direction of thedeflection puller members. For example, an arrangement wherein the twodeflection puller members 42 are anchored at different distances fromthe distal ends of the compression coils 44 allows a long reach curve ina first plane and a short reach curve in a plane 90 degree from thefirst, i.e., a first curve in one plane generally along the axis of theintermediate section 14 before it is deflected and a second curve distalto the first curve in a plane transverse, and preferably normal to thefirst plane. The high torque characteristic of the catheter intermediatesection 14 reduces the tendency for the deflection in one direction todeform the deflection in the other direction. Suitable deflectioncontrol handles and parts thereof for use with such a catheter aredescribed in U.S. patent application Ser. No. 08/924,611, filed Sep. 5,1997, entitled “Omni-Directional Steerable Catheter”, Ser. No.09/130,359, filed Aug. 7, 1998, entitled “Bi-Directional Control Handlefor Steerable Catheter”, and Ser. No. 09/143,426, filed Aug. 28, 1998,entitled “Bidirectional Steerable Catheter with Bidirectional ControlHandle”, the entire disclosures of which are hereby incorporated byreference.

For adjusting the mapping assembly 17 by means of a third puller member,e.g., the contraction wire 35, a distal end of the contraction wireextending between the two deflection puller members 42 within thecontrol handle is anchored in the control handle for actuation by meansof a rotational control assembly 200. In the illustrated embodiment ofFIG. 23, the rotational control assembly 200 includes an outerrotational cam 202, a pulley shaft 204 and a pulley 206 around which thethird puller member 35 is wrapped. The cam 202 closely surrounds theproximal portion 116 of the control handle and as the proximal portion116 has a cylindrical shape, the rotational cam is in a circumferentialrelationship with the proximal portion so that it can rotate about alongitudinal central axis 205 of the proximal portion 116 on an outersurface 208 of the proximal portion and serve as a rotational interfacebetween the user and internal components of the rotational controlassembly 200. In that regard, the outer surface 208 is sufficientlysmooth such that the cam 202 can rotate on it with minimal frictionalforces. A friction-inducing surface can be provided on an outer surfaceof the cam 202 to facilitate manipulation and rotation by the user.

The proximal portion 116 under the cam 202 has two diametricallyopposing guide slots 208 extending axially in a direction parallel tothe longitudinal axis 205 of the proximal portion 116. The cam 202 hason its inner surface two opposing helical tracks or grooves 210extending about the longitudinal axis 205. The helical grooves 210 areconfigured such that any plane perpendicular to the longitudinal axisintersects the grooves along a diameter of the proximal portion 116. Theshaft 204 extends diametrically between the two guide slots 208,traversing the interior of the proximal portion at an angle generallyperpendicular to the longitudinal axis 205. The guide slots 208 aresized so that the shaft 204 can pass through the slots and have each ofits two opposing ends 212 be received in a respective helical groove onthe inner surface of the cam. As such, the length of the shaft isgreater than an outer diameter of the proximal portion 116 but lesserthan an outer diameter of the cam 202. Accordingly, the helical grooves210 are sized to receive the ends 212 and allow the ends to slidetherein.

Mounted on the shaft, for example, at or near a midpoint of the lengthof the shaft, is the pulley 206 on which the third puller member iswrapped. The third puller member which can be any suitable material,including a puller wire or contraction wire, has a proximal end (notshown) that is anchored to the control handle or to any other rigidlymounted component within the control handle, at a location distal of thedistal ends of the guide slots. Longitudinal movement of the contractionwire 35 relative to the catheter body 12 can effectuate, for example,contraction and expansion of the mapping assembly 17.

With reference to embodiment of FIGS. 1, 23 and 24, the rotationalcontrol assembly 200 is positioned proximal the deflection controlassembly 74, although it is understood that it can be positioned distalthe deflection control assembly 74. In the disclosed embodiment, the cam202 is mounted on the proximal portion 116 of the control handle. Thecam 202 can be formed from as a solid piece that slides onto theproximal portion and is snap-fitted over the two ends 212 of the shaft204. Alternatively, the cam can be formed of two halves that aresnap-fit to each other or joined by glue or sonic welding over the twoends of the shaft.

In operation, the rotational control assembly 200 is manipulated bymeans of the cam 202. As a user holds the control handle 16 and rotatesthe cam with his thumb and forefinger to contract or expand the mappingassembly, the two opposing helical tracks 210 on the inner surface arerotated relative to the proximal portion 116 thereby exerting a force onthe shaft 204 via the ends 212 received in the tracks 210 todiametrically spin about the central longitudinal axis 205 of thecontrol handle. However, because the shaft 204 extends through the guideslots 208 of the proximal portion 116, the guide slots limit the shaftto a translational movement proximally or distally along thelongitudinal axis depending on the direction of rotation of the cam 202as the ends 212 slide in the helical tracks 210. As the shaft 204 movesproximally or distally, the pulley 206 thereon correspondingly movesproximally or distally thereby drawing or releasing the third pullermember 35. Advantageously, the rotational control assembly provides amultiplied linear motion of the third puller member, with greatersensitivity in the amount of motion controlled by the user. In thedisclosed embodiment of FIG. 24, each helix 210 has a rotation of about540° (360°+180°. However, it is understood that the rotation of eachhelix can range between about 180° to 720° depending on how muchcontraction/deflection and/or how much sensitivity is desired.

Lead wires and other components (e.g., thermocouple wires, cables,irrigation tubing) extending through proximal portion 116 in aprotective tubing so as not to interfere with the interior components ofthe rotational control assembly.

In use, a suitable guiding sheath is inserted into the patient with itsdistal end positioned at a desired mapping location. An example of asuitable guiding sheath for use in connection with the present inventionis the Preface™ Braiding Guiding Sheath, commercially available fromBiosense Webster, Inc. (Diamond Bar, Calif.). The distal end of thesheath is guided into one of the chamber, for example, the atria. Acatheter in accordance with the present invention is fed through theguiding sheath until its distal end extends out of the distal end of theguiding sheath. As the catheter is fed through the guiding sheath, themapping assembly 17 is straightened to fit through the sheath. Once thedistal end of the catheter is positioned at the desired mappinglocation, the guiding sheath is pulled proximally, allowing thedeflectable intermediate section 14 and mapping assembly 17 to extendoutside the sheath, and the mapping assembly 17 returns to its originalshape due to the shape-memory of the support member 54.

By manipulating and rotating the deflection aim 75 of the deflectioncontrol assembly 74 to deflect the intermediate section 14, the mappingassembly 17 is then inserted into a pulmonary vein or other tubularregion (such as the superior vena cava, or inferior vena cava) so thatthe outer circumference of the generally circular main region 39 of theassembly 17 is in contact with a circumference inside the tubularregion. Turning the deflection arm 75 in one direction deflects theintermediate section 14 to that direction. Turning the deflection 75 inthe opposite direction deflects the intermediate section 14 to thatopposite direction. Tension of the deflection 75 is adjusted bymanipulating and rotating the dial 101. Turning the dial 101 in onedirection increases the tension. Turning the dial 101 in the oppositiondirection decreases the tension. Preferably at least about 50%, morepreferably at least about 70%, and still more preferably at least about80% of the circumference of the generally circular main region is incontact with a circumference inside the tubular region.

The circular arrangement of the electrodes 26 permits measurement of theelectrical activity at that circumference of the tubular structure sothat ectopic beats between the electrodes can be identified. The size ofthe generally circular main region 39 permits measurement of electricalactivity along a diameter of a pulmonary vein or other tubular structureof or near the heart because the circular main region has a diametergenerally corresponding to that of a pulmonary vein or the coronarysinus. By manipulating and rotating the cam 202 of the rotationalassembly 200, the assembly 17, in particular, the generally circularmain region 39, is contracted to fit the pulmonary vein or other tubularstructure.

In accordance with a feature of the present invention, rotational motionof the cam results in linear motion of the shaft and the pulley alongthe central longitudinal axis of the control handle. The shaft ridesalong the helical grooves of the cam as it is rotated. The opposinglinear guide slots of the proximal portion of the control handle ensurethat the shaft maintains its general perpendicular orientation resultingin linear motion of the shaft relative to the proximal portion. As theshaft translates along the longitudinal axis, the pulley is also movedwherein its linear displacement results in twice the linear displacementof the third puller member. In the disclosed embodiment, the contractionwire is drawn proximally by the rotational control assembly to tightenand decrease the diameter of the generally circular region 39 when thecam is turned in one direction. By turning the cam in the oppositiondirection, the contraction wire 35 is released to release the generallycircular region 39 such that it expands its diameter.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. It is understood that the present invention isapplicable to multiplying linear motion of a puller wire, contractionwire, or any other object requiring insertion, removal, or tensioningwithin a medical device, including the disclosed electrophysiologycatheter. As understood by one of ordinary skill in the art, thedrawings are not necessarily to scale. Accordingly, the foregoingdescription should not be read as pertaining only to the precisestructures described and illustrated in the accompanying drawings, butrather should be read consistent with and as support to the followingclaims which are to have their fullest and fair scope.

What is claimed is:
 1. A medical device comprising: an elongated body; amember distal the elongated body, the member having a configuration; acontrol handle proximal the elongated body, the control handle having alongitudinal axis; a control assembly comprising a rotational cam, ashaft, and a pulley, the rotational cam being in a circumferentialrelationship with a portion of the control handle and adapted forrotation about the longitudinal axis, the rotational cam having an innersurface with two opposing helical tracks, the portion of the controlhandle having two opposing linear guide slots extending in parallel withthe longitudinal axis, the shaft extending along a diameter of theportion of the control handle generally perpendicular to thelongitudinal axis, the shaft having two opposing ends, each of whichextends through a respective guide slot and is received in a respectivehelical track, the pulley being mounted on the shaft; and a pullermember wrapped about the pulley, wherein rotation of the rotational camabout the longitudinal axis by a user actuates movement of the shaftrelative to the control handle along the longitudinal axis, therebyacting on the puller member via the pulley to change the configurationof the member.
 2. A medical device of claim 1, wherein the member iscontracted when the user rotates the rotational cam.
 3. A medical deviceof claim 1, wherein the member is expanded when the user rotates therotational cam.
 4. A medical device of claim 1, wherein the member isdeflected.
 5. A medical device of claim 1, wherein the shaft rotatesabout its longitudinal axis and translates along the longitudinal axisof the control handle while remaining generally perpendicular theretowhen actuated by the rotational cam.
 6. A medical device of claim 1,wherein the rotational cam is outside of the portion of the controlhandle with which it is in a circumferential relationship.
 7. A medicaldevice of claim 1, wherein rotation of the cam in one direction expandsthe member and rotation of the cam in an opposite direction contractsthe member.
 8. A medical device of claim 1, wherein the ends of theshaft ride along their respective helical tracks as the cam is rotated.9. A medical device of claim 1, wherein the shaft remains generallyperpendicular to the longitudinal axis of the control handle as the camis rotated.
 10. A medical device of claim 1, wherein the shaft moveswithin the linear guide slots as the cam is rotated.
 11. A catheter ofclaim 1, wherein the shaft remains generally perpendicular to thelongitudinal axis of the control handle as the cam is rotated.
 12. Acatheter of claim 1, wherein the shaft moves within the linear guideslots as the cam is rotated.
 13. A catheter comprising: a catheter body;a deflectable intermediate section distal the catheter body; a mappingassembly distal the intermediate section, the mapping assembly having agenerally circular portion; a control handle proximal the catheter body,the control handle having a longitudinal axis and comprising: adeflection control assembly; and a rotational control assemblycomprising a rotational cam, a shaft, and a pulley, the rotational cambeing in a circumferential relationship with a portion of the controlhandle and adapted for rotation about the longitudinal axis, therotational cam having an inner surface with two opposing helical tracks,the portion of the control handle having two opposing guide slotsextending in parallel with the longitudinal axis, the shaft extendingalong a diameter of the portion of the control handle generallyperpendicular to the longitudinal axis, the shaft having two opposingends, each of which extends through a respective guide slot and isreceived in a respective helical track, the pulley being mounted on theshaft; first and second puller members responsive to the deflectioncontrol assembly adapted to deflect the intermediate section; and athird puller member responsive to the rotational control assemblyadapted to contract the generally circular portion of the mappingassembly.
 14. A catheter of claim 13, wherein a proximal end of thethird puller member is anchored inside the control handle at a locationdistal of the shaft.
 15. A catheter of claim 13, wherein the rotationalcam is outside of the portion of the control handle with which it is ina circumferential relationship.
 16. A catheter of claim 13, wherein themapping assembly is contracted when the user rotates the rotational cam.17. A catheter of claim 13, wherein the mapping assembly is expandedwhen the user rotates the rotational cam.
 18. A catheter of claim 13,wherein the shaft rotates about its longitudinal axis and translatesalong the longitudinal axis of the control handle while remaininggenerally perpendicular thereto when actuated by the rotational cam. 19.A catheter of claim 13, wherein the rotational cam is outside of theportion of the control handle with which it is in a circumferentialrelationship.
 20. A catheter of claim 13, wherein rotation of the cam inone direction expands the mapping assembly and rotation of the cam in anopposite direction contracts the mapping assembly.
 21. A catheter ofclaim 13, wherein the ends of the shaft ride along their respectivehelical tracks as the cam is rotated.